Fibrotic diseases, especially in the lung, liver, pancreas, skin and kidney, account for as much as 45% of deaths in the world (Friedman, S L, et al. Science Translational Medicine, 5(167):167sr1 (2013)). With regard to liver disease, there are no antifibrotic agents for liver fibrosis and cirrhosis available for use in humans. There is a clinical urgency for hepatic fibrosis therapies because of the increasing disease prevalence from viral, obesity-related and alcohol-related fibrosis and cirrhosis as well as the shortfall in liver donations for transplants. In 1985, hepatic stellate cells (HSC) were identified as the main culprit in developing liver fibrosis by overexpressing extracellular matrix components (Friedman S L, et al., PNAS, 82(24):8681-5 (1985)). Pancreatic stellate cells (PSCs) are myofibroblast-like cells that play a pivotal role in the development of pancreatic fibrosis, pancreatitis and pancreatic cancer (Omary. M. B., et al., J. Clin. Invest. 117(1):50-59 (2007)). In response to pancreatic injury or inflammation, quiescent PSCs are activated to myofibroblast-like cells and express a-smooth muscle actin, very similar to HSCs.
Existing treatments for liver fibrosis have several short comings. Some treatments affect HSCs. A number of hepatoprotectants that attenuate or neutralize upstream inflammatory responses, and thus HSC activation, have been studied in vitro and in vivo. Vitamin E was evaluated in clinical trials in nonalcoholic steatohepatitis (NASH) and demonstrated that histological liver injury was attenuated although no antifibrotic effect was demonstrated (Sanyal, A J., et al., New Eng, J. Med.e, 362(18):1675-85 (2010)).
Hepatocyte growth factor (HGF) is reported to modulate HSC proliferation, collagen synthesis, and TFG-β expression. Delivery of HGF by gene therapy or injecting a recombinant protein prevented the progression of experimental liver fibrosis. However, there are concerns of using HGF or HGF mimetics that would stimulate hepatocyte growth and increase the potential risk of oncogenesis (Fallowfield, J A., American Journal of Physiology-Gastrointestinal and Liver Physiology, 300(5):G709-G15 (2011)).
Agents that would prevent HSC activation or proliferation have also been investigated. HSC activation is associated with low-level of PPAR-r expression. Upregulation of PPAR-r or addition of PPAR-r ligands reverse the HSC activation. A few PPAR-r ligands, glitazones, have been tested in animal models but only marginally slowed fibrosis progression early in the disease course (Leclercq, I A, et al., Gut, 55(7):1020-9 (2006)).
Statins, HMG-CoA reductase inhibitors, are also known to inhibit HSC proliferation in vitro and provided beneficial effects on portal hypertension and on angiostensin II-induced inflammation in liver fibrosis models. For example, early atorvastatin treatment attenuated HSC activation and collagen deposition after bile duct ligation in rats; however, atorvastatin was not effective when the treatment was initiated once fibrosis was established (Trebicka, J., et al., Journal of Hepatology, 53(4):702-12 (2010)), indicating it was useful only as a preventative, not a therapeutic.
The renin-angiotensin system plays important roles in liver fibrogenesis and portal hypertension. Studies indicate that angiotensin-converting enzyme inhibitors and ATIR antagonists, sartans, could reduce fibrosis (Yang, L., et al., Journal of Hepatology, 43(2):317-23 (2005)). Treating patients with chronic hepatitis C virus (HCV) with the AT1R antagonist losartan slowed fibrosis progression and profibrogenic genes (Colmenero, J., et al., American Journal of Physiology Gastrointestinal and Liver Physiology, 297(4):G726-34 (2009)).
TGF-β is the key effector in the pathogenesis of liver fibrosis. Reducing or inhibiting TGF-β synthesis and signaling have been thought to be an important therapeutic target. Diverse strategies to inhibit TGF-β effects include using TFG-β neutralizing antibodies, decoy receptors, siRNA and oligonucleotides. A few TGF-β related molecules showed antifibrotic effects in animal models, however, it would be difficult to target HSC because TGF-β receptors are widely expressed on all cell types and such inhibitors could trigger autoimmune diseases or cellular dedifferentiation.
Chronic pancreatitis (CP) is a disease characterized by progressive and irreversible destruction of pancreas structure and function (Braganza, J. M., et al., Lancet, 377(9772):1184-97 (2011)). CP is accompanied by pancreatic fibrosis and constant abdominal pain. The management of CP and CP-associated pain is challenging since CP is currently an incurable condition. No agents have emerged in humans, resulting in a significantly undeserved CP patient population. CP is recognized by significant fibrosis. Pancreatic fibrogenesis is mainly orchestrated by PSCs. During pancreatic damage or disease, quiescent PSCs undergo activation and transform to proliferative, fibrogenic and contractile myofibroblasts that facilitate collagen deposition and lead to fibrotic tissue. Therefore, activated PSCs are a major target for antifibrotic and anti-pain therapies targeting the pancreas (Omary, M. B., et al., J. Clin. Invest. 117(1):50-59 (2007)). However, like HSCs, the lack of methods to specifically target and affect activated PSCs in vivo hampers this strategy.
During fibrogenesis and upon activation of HSCs or PSCs, many fibrosis-associated molecules are highly upregulated and contribute to the development of fibrosis and its complications. These molecules include, but are not limited to, PDGF, TGFβ, CTGF, MMPs, TIMPs and collagens (Friedman, S. L., Nat Rev Gastroenterol Hepatol. 7(8):425-36 (2010)). A common antifibrotic strategy is inhibiting the regulation of one of many fibrosis-associated molecules in vivo. Inhibition of one fibrosis-associated molecule would provide some anti-fibrosis efficacy; however, since fibrogenesis is a complicated process associated with multiple pathways that are involved with many fibrogenic molecules, such methods would not be highly efficient to stop or reverse fibrosis. Simultaneous inhibition or down-regulation of multiple fibrosis-associated molecules will demonstrate strong anti-fibrotic efficacy, however, it is difficult to target multiple molecules simultaneously in physiological conditions particularly by utilizing a single drug molecule.
Therefore, it is an object of the invention to provide compositions and methods for treating fibrotic disease, including liver fibrosis and pancreatic fibrosis.
It is another object of the invention to provide compositions and methods for simultaneously inhibiting or down-regulating multiple fibrosis-associated molecules in physiological conditions.
It is another object of the invention to provide compositions and methods for reducing, inhibiting, or reversing liver fibrosis and other diseases such as cirrhosis and its complications.
It is still another object of the invention to provide methods and compositions for reducing or inhibiting liver inflammation.
Another object of the invention is a method for treating fibrosis of other organs and its related complications, for example, pancreatic fibrosis, chronic pancreatitis, and its complications, such as pain.